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Chahoua Geckos and Underbites


Michael Pannone
The Chahoua Chamber

Updated December 30, 2023


Whether you've been keeping chahoua for some time or you are new to the species, you've probably seen "underbites" mentioned in reference to these geckos. One of the most common concerns I hear from hobbyists is about the dreaded underbite, especially as related to Mainland/GT chahoua.

"Does he have an underbite?"

"Did his parents have underbites?"

"Has he always had an underbite?"

"Can I fix the underbite?"

Over the years, I've seen many people comment that underbites are a result of sustained, generational inbreeding in old Mainland/Grand Terre animals, but I've also seen some unrelated animals - Pine Island and Grand Terre - produce offspring with underbites as well. I decided to dig further into the specifics - talking to breeders about lineage, diets, husbandry, supplementation, laying schedules and much more.

Over many years of talking about this topic on and off, I have come to the conclusion that do not think underbites are the culprit of inbreeding, but rather a consequence of inadequate calcium reserves in laying females and poor calcium supplementation in young animals. Here is the summary of my research:

I owned a chahoua with a severe underbite, Scooby, who I bought as a hatchling with the "fat lip" as I affectionately called it. When I got Scooby, I asked the breeder several questions and probed into what might have caused his jaw deformity. I believe that the breeder was very honest and upfront with me about the situation, and that is why I felt comfortable purchasing him, so I’ll start by sharing Scooby’s story.


Scooby and the "Fat Lip"


Scooby's parents were both unrelated Grand Terre animals from two different breeders and each was 5 1/2 years old at the time that he hatched. In the 3 prior years they have were paired, the female consistently laid 3 clutches and produced beautiful, healthy babies. In this particular year, she decided to drop a “surprise” 4th clutch and calcium-crashed directly after laying. The other egg turned out perfectly fine but Scooby came out with an underbite and was the first imperfect baby the pair ever produced.

I always considered this situation when hearing of or looking at animals with underbites, and I started to notice a pattern: a lack of calcium in the mother while laying was frequently a part of the circumstance. I am not saying that this is necessarily breeder error, as we don’t have much control over how many clutches a female decides to lay in a year, especially if she decides to lay an extra at the end of the season when her calcium reserves might be depleted. It is common knowledge that these geckos are calcium-sensitive so it's logical to think that at the end of a season, the female may have been low on calcium, squeezed out one last clutch, and those babies suffered as a result of her deficiency.

Less Calcium, More Underbites

I have a longtime friend who lives near a local laboratory that has kept and bred New Caledonian species, including some Pine Island and Grand Terre chahoua pairs, for many years. The scientist who manages these animals only feeds baby food with a bit of calcium and unsupplemented crickets. Season after season, every offspring from every pair is born with an underbite.

I think the results from that lab are quite interesting: with 6-7 pairs of unrelated animals from different locales producing 100% of babies with underbites, the logical question becomes what they have in common. The first and most obvious is husbandry and diet; the second could be incubation which I know nothing about. Baby food with just a bit of added calcium, and insects that are not dusted in a calcium supplement, are not enough to properly sustain chahoua. Much like in Scooby's case, lower or insufficient calcium is a common link. 

I want to be clear that I think there are different types of calcium deficiency:

Situation 1: The laying female has low calcium reserves when laying eggs, the low calcium is somehow passed onto the eggs and embryo(s) and results in an underbite. This calcium deficiency can be from bad diet or being bred too early. This is what I presume happened to Scooby.

Situation 2: A diet low in calcium is offered to a young, developing, healthy chahoua and impacts the animal's jaw structure while growing, resulting in an underbite.

"Mostly Grand Terre chahoua have underbites - not Pine Island animals"

In comparison to Pine Island chahoua, Grand Terre animals have the reputation of being more prone to underbites and many people assert that this is due to a lack of genetic diversity and inbreeding. I am not so sure that there couldn’t be another explanation…

According to my research, Grand Terre animals were imported to the U.S. first and the Pine Island chahoua came about a decade later. Obviously, remarkable research and insight has been gained on the front of reptile nutrition in the last 20 years, and really, just in the last 10 years. For a very long time, baby food was the standard when feeding frugivorous geckos. After some trial and error, people realized that they needed to supplement the baby food with calcium, and then a while later, prepared diets such as Repashy Crested Gecko Diet or Pangea Gecko Diet were born. Now we are generations later and still making progress!

It's quite likely that when the Grand Terre chahoua arrived in the mid- to late- 1980s, they were fed primarily baby food and/or insects because those were the best methods available at the time. Since this is not a complete or sufficient diet (and if my above assumptions are true), and considering the calcium-sensitive nature of chahoua, these geckos likely started producing a high number of offspring with underbites. As the numbers increased and feeding practices stayed the same, more and more chahoua with underbites were born. Today, I believe we are seeing fewer animals with underbites because we know more about how to correctly feed, supplement, and breed them which means this deformity is showing up less frequently.

By the time the Pine Island animals arrived in captive collections, a decent number of GT chahoua had been produced in captivity with underbites, so that is what people came to expect of the Grand Terre locales. I have certainly seen a few PI animals with underbites, but GT chahoua suffer from the stigma moreso.

Also consider: The New Caledonian geckos as a group have proven to be extremely resistant to the effects or mutations often associated with inbreeding, even over prolonged periods of time and multiple generations.

In summary, it is most likely that Grand Terre chahoua get a bad reputation for underbites and “being too inbred” when it is actually human error and misunderstanding of their nutritional needs that caused this problem in the first place.

Scooby's Story - Continued!

In late 2010, I decided to pair Scooby to a Grand Terre female that I owned because I was curious about whether or not the underbite was a truly genetic trait, as some have suggested. It was always my intention to keep any offspring in my possession considering the sensitivity of breeding an "imperfect" animal.

The pair bonded, the female became gravid and later laid two eggs. One was infertile and the other was fertile and perfect, so I incubated it for 130-something days and out came Scooby's daughter, who is now named Wilma.


Wilma hatched out with a perfectly aligned jaw and reached adulthood with a perfectly shaped jaw and mouth:

Chahoua - Mainland -1.jpg

There are some folks who would never breed an animal with an underbite, and I understand that position, especially if the gecko is female. If a female has an underbite, and it was indeed caused by one of the theories above, then I worry that the breeding and laying process could be even more taxing on an animal that suffered some calcium deficiency at some point in life. Once again, considering the controversy of this deformity, I planned to keep any offspring from this pairing in my own collection.

I see Wilma as a strong case for the theories above, especially considering that Scooby had one of the most pronounced underbites I have ever seen in a chahoua. I do not know what the results would have been if I bred a female chahoua with an underbite...would her calcium deficiency impact embryos and future generations? Would it impact her ability to breed and lay eggs? This I do not know, but it's possible. There is still more testing to be done.

"Can I fix my chahoua's underbite?"

Like the sections above, I don't have a 100% conclusive answer to this question but there seems to be some evidence that the answer is "yes," so long as it's managed and supplemented correctly from a very young age. The severity of the underbite is also a consideration. Over the years, I have purchased a few chahoua from different breeders that came to me with slight underbites. Most of these animals were quite young - less than four months old - and I have been completely able to correct the deformity over time with the correct diet and calcium supplementation. I am referencing 3-4 animals with underbites out of 300+ total chahoua that I have owned, bred and hatched since 2009.

So, how did I do it? Quite simply, I added calcium to the animal's diet. I use the Pangea line of diets and also formulate my own chahoua diet with added calcium, and also increased the frequency of feeding supplemented insects. When done consistently, and closely watched, this has eliminated any signs of an underbite. I highly doubt that this method would be effective on an older animal, as they are more mature and have finished growing, so the damage for older geckos is already done. However, with animals six months or younger, I believe that there is a good chance that additional calcium can go a long way towards eliminating underbites in adult chahoua... and overtime, some of the stigma around them.​

"Can I breed my chahoua even though it has an underbite?"

Can you? Yes. Should you? I think it depends heavily on your specific animal. If you produced or purchased a young animal that had an underbite, and you were able to fix it with additional calcium supplementation, and the gecko no longer has an underbite at breeding age, then I think you can probably breed your gecko safely. If you choose to do this, keep a close eye on offspring to check for underbites in the future.  

If you have an adult chahoua with an underbite, especially a female, I would strongly caution against breeding that gecko because calcium deficiency is something she experienced into adulthood. With chahoua being so dependent upon calcium supplementation for their health, I would not feel comfortable breeding an adult female with sustained evidence of calcium deficiency (an underbite) because breeding and laying eggs will be a larger strain on such a gecko, and I think there could be a stronger chance of offspring potentially suffering from underbites as well because of the mother's condition. 

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